not sure if I'm posting in the right place but, I'm getting ready to run all my water lines but I don't know what size to run 3/4 or 1/2 from the pump to the bypass(which I guess is to be set at 15#) then to the 4 port thermostat and to to logs and over the transom exhaust.....are all the water lines the same size or do they change size anywhere. Can someone help me out here also i'm running a tunnel ram w/ 2 -600 holley's on a BBC ,Do I want to run 5/16 or 3/8 fuel line or does it matter . I'm putting this together from scratch and could use some expert help here................................... ......................................t hank's
                                                                                            motorhome6

I'm running 5/8 (hose size) on the water and 5/16 on the fuel hoses until it gets to the engine, it drops to 3/8. Gonna depend on the pressure and actual volume you need whether you need more hose or not. I have 2 750's and at cruise speed (55 or so) pressure is fine at 5 lbs. No idea what it is at WOT, boats never been totally there, and when near there, kinda hard to convince anyone to go look at it, lol.

All the plumbing fittings you need are 1/2 inch that I have seen, for the most part, on the water system, though mine drops to 3/8 for the header outlet. (Pipe fitting sizes)  Don't confuse pipe fitting size with hose size. The oulet from a Berk pump is 3/8 NPT, so go from there. Regular heater hose size (5/8) is fine off the barb fittings. Idea is to keep the temp in the 160-180 range (Low IMO, but these are boats, not cars),

I'm gonna be picking 2sav's brain this winter in converting the Moo to all braided stainless and don't know what AN sizes I need. Just gathering chit blindly right now, lol.

Dunno if I answered anything or just ranted.

Ray

I just finished mine and I have the same setup you have. For the fuel lines I ran 3/8" feeding a tunnel ram with two Holley 600's. I used stainless hard lines but I think the inside diameter doesn't differ much. I ran 3/4" from the pump into a 3/4" to 1/2" tee into the inlets.  From the thermostat housing I ran two 1/2" out to the back of the motor into a 1/2" to 3/4" tee and out the back. Put two 1/2" valves before the tee. Also, off the front of the intake I ran another 1/2" line to a Rewarder check valve and 1/2" lines to the OT headers. Here's a pic just before it was finished. I didn't have the valves and the lines off the thermostat run straight out the back in the pic.

i realy like that what was the cost? cheeper than steel braided?

Probably close to the same. I had some fittings from another project and was able to use tubing from my last engine so hard to say. The problem is bending and having the right tools to bend stainless.

Just used a heavy duty hand bender and a lot of muscle. Came out really nice. I just finished it and will try it out tomorrow morning at elsinore. I'll let you know how it works out as far as the amount of water to the headers and engine temp.